1. Field
The present invention relates to a method for manufacturing a multilayer structure sheet for manufacturing an optical information recording medium having a multilayer structure with a plurality of recording layers, and an optical information recording medium having a multilayer structure with a plurality of recording layers.
2. Description of Related Art
Conventionally, as a method for manufacturing an optical information recording medium having a multilayer structure with a plurality of recording layers, a method using a multilayer structure sheet having laminates of a recording layer and a pressure sensitive adhesive layer is known in the art (e.g., Patent Literature 1). To be more specific, a multilayer structure sheet described in Patent Literature 1 has a release film attached to each of outer surfaces of a laminate of recording and pressure sensitive layers. By peeling this release film off the multilayer structure sheets and stacking and sticking the sheets over a substrate repeatedly one on top of another, an optical information recording medium having a multilayer structure can be obtained. In this type of manufacturing method using a multilayer structure sheet, a plurality of optical information recording media can be manufactured in bulk by preparing a large-size multilayer structure sheet.
However, the multilayer structure sheet as described in Patent Literature 1 is configured to have a release film attached to the recording layer, and thus involves a risk of cracking occurring in the recording layer when the release film is peeled off. With this in view, there is proposed a multilayer structure sheet so configured as to have a release film not directly attached to any recording layer (e.g., Patent Literature 2). To be more specific, the multilayer structure sheet described in Patent Literature 2 has a multilayer structure comprising a pressure sensitive adhesive layer, a recording layer and a release assisting layer arranged in this order, and a release film is attached to each of the outermost layers that are the pressure sensitive adhesive layer and the release assisting layer. With this configuration in which the recording layer is sandwiched between the pressure sensitive adhesive layer and the release assisting layer as described above so that the release film is not directly attached to any recording layer, the possibility of cracking in the recording layer which would occur when the release film is peeled off can be reduced.